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From Ayub M <hia...@gmail.com>
Subject Cassandra collection tombstones
Date Fri, 25 Jan 2019 05:29:28 GMT
I have created a table with a collection. Inserted a record and took
sstabledump of it and seeing there is range tombstone for it in the
sstable. Does this tombstone ever get removed? Also when I run
sstablemetadata on the only sstable, it shows "Estimated droppable
tombstones" as 0.5", Similarly it shows one record with epoch time as
insert time for - "Estimated tombstone drop times: 1548384720: 1". Does it
mean that when I do sstablemetadata on a table having collections, the
estimated droppable tombstone ratio and drop times values are not true and
dependable values due to collection/list range tombstones?
CREATE TABLE ks.nmtest (
    reservation_id text,
    order_id text,
    c1 int,
    order_details map<text, text>,
    PRIMARY KEY (reservation_id, order_id)
) WITH CLUSTERING ORDER BY (order_id ASC)

user@cqlsh:ks> insert into nmtest (reservation_id , order_id , c1,
order_details ) values('3','3',3,{'key':'value'});
user@cqlsh:ks> select * from nmtest ;
 reservation_id | order_id | c1 | order_details
----------------+----------+----+------------------
              3 |        3 |  3 | {'key': 'value'}
(1 rows)

[root@localhost nmtest-e1302500201d11e983bb693c02c04c62]# sstabledump
mc-5-big-Data.db
WARN  02:52:19,596 memtable_cleanup_threshold has been deprecated and
should be removed from cassandra.yaml
[
  {
    "partition" : {
      "key" : [ "3" ],
      "position" : 0
    },
    "rows" : [
      {
        "type" : "row",
        "position" : 41,
        "clustering" : [ "3" ],
        "liveness_info" : { "tstamp" : "2019-01-25T02:51:13.574409Z" },
        "cells" : [
          { "name" : "c1", "value" : 3 },
          { "name" : "order_details", "deletion_info" : { "marked_deleted"
: "2019-01-25T02:51:13.574408Z", "local_delete_time" :
"2019-01-25T02:51:13Z" } },
          { "name" : "order_details", "path" : [ "key" ], "value" : "value"
}
        ]
      }
    ]
  }
SSTable: /data/data/ks/nmtest-e1302500201d11e983bb693c02c04c62/mc-5-big
Partitioner: org.apache.cassandra.dht.Murmur3Partitioner
Bloom Filter FP chance: 0.010000
Minimum timestamp: 1548384673574408
Maximum timestamp: 1548384673574409
SSTable min local deletion time: 1548384673
SSTable max local deletion time: 2147483647
Compressor: org.apache.cassandra.io.compress.LZ4Compressor
Compression ratio: 1.0714285714285714
TTL min: 0
TTL max: 0
First token: -155496620801056360 (key=3)
Last token: -155496620801056360 (key=3)
minClustringValues: [3]
maxClustringValues: [3]
Estimated droppable tombstones: 0.5
SSTable Level: 0
Repaired at: 0
Replay positions covered: {CommitLogPosition(segmentId=1548382769966,
position=6243201)=CommitLogPosition(segmentId=1548382769966,
position=6433666)}
totalColumnsSet: 2
totalRows: 1
Estimated tombstone drop times:
1548384720:         1

Does tombstone_threshold of compaction depend on the sstablemetadata
threshold value? If so then for tables having collections, this is not a
true threshold right?

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